The present invention relates to an apparatus and method for dispensing dry material and, more particularly, to an apparatus and method for accurately measuring and dispensing dry material into a portable container.
Dry agrichemicals, such as herbicides, fertilizers, pesticides, fungicides, and the like, are widely used by the agricultural community in many applications. For example, a farmer wishing to fertilize his planted crops might visit a supplier of agrichemicals and purchase a predetermined amount of dry agrichemical for later dilution to fertilize a given number of acres. In many cases, the farmer will only know the required number of acres to be fertilized. The material supplier will calculate therefrom the amount of dry fertilizer required for the given acreage.
Amazingly, many modern dry agrichemicals are currently concentrated to the extent that a small quantity of material, i.e., a few ounces, can cost several hundred dollars. Because the highly concentrated material is very expensive, it is in the best interest of the supplier and the buyer that the material be measured accurately. Additionally, because the dry agrichemicals are so highly concentrated, exposure thereto can be dangerous. It is thus desirable to avoid direct contact with the materials while measuring and dispensing them. It is further desirable to measure and dispense the materials in an enclosure in order to avoid contact with or breathing of the dust produced by the materials.
U.S. Pat. No. 5,803,673 to Reinsch et al. discloses a device and method for transportation and metering of precise amounts of particulate matter. An outer enclosure which contains the particulate matter is connected by a conduit for transporting the particulate matter in an entrained pneumatic gas stream to a cyclone separator. The separator separates the particulate matter from the pneumatic gas in which the particulate matter is entrained. An air lock, including a rotor having a plurality of vanes, is located within an air lock housing to meter material being dispensed. The air lock is operated by an electrical drive motor and a magnetic proximity switch provides feedback for measuring the amount of particulate matter dispensed.
U.S. Pat. No. 4,756,348 to Moeller discloses an apparatus for controlling discharge of plastic materials from a supply hopper 11 to a blending hopper 14. Material is housed in hopper 11 and is transported through a generally vertical tube to the weigh hopper 14 through a valve means which valve means is controlled by a control assembly. The valve disclosed in the Moeller patent requires three positions. A fully opened position, a partially closed position and a completely closed position. When initially filling the weigh hopper, the valve is opened to the fully open position. When the weight becomes close to the desired amount, a microprocessor activates the control assembly which in turn closes the valve to the partially closed position so that the material exits the tube more slowly. Finally, when the weight of the material in the weigh hopper further approaches the desired quantity, the microprocessor sends a signal which fully closes the valve.
Similarly, U.S. Pat. No. 4,300,600 to Tetenborg et al. discloses an apparatus for filling and weighing large capacity sacks. The sacks are successively suspended from holding devices by their mouths and filled with pourable material through a conduit equipped with a flap. Initially, the flap is only slight opened. When the sack becomes heavy enough to rest upon a support provided, the flap fully opens until the contents of the sack reach a predetermined final weight, whereupon filling is then completed at a trickle rate.
It is desirable in the agricultural industry to provide an economical and highly accurate dispensing and measuring apparatus for dry material.